1. Field of the Invention
The present invention relates to an image processing device and method for displaying a half tone image, and more particularly, to an image processing device and a method for artificially increasing the number of shades to display by distributing an error between an original image and a display image.
2. Description of the Related Art
Recently, displays have become very important for man-machine interfaces in an advanced information society, and thin, light-weight, flat display panels are in strong demand. These display panels are, for example, plasma display panels (PDPs), electronic luminescence (EL) panels, fluorescent display panels, or liquid crystal display (LCD) panels.
The display panels presently marketed have a problem in display quality. In particular, they have a problem in displaying a halftone image involving shades or gradations. Among the display panels, the plasma display panels are drawing attention because they are capable of providing a large screen and displaying a clear image. In the plasma display panel, recently, higher level gray scales in many display lines has become necessary with the requirements of a larger display size, a larger number of pixels (cells) and full color display in a display panel.
Conventionally, there are several techniques to display shades on a display panel. One of the techniques is dithering, which artificially increases the number of shades to display with the use of patterns of pixels. Dithering has a problem of producing peculiar patterns and lowering resolution.
Another technique is "error distribution," which increases the number of shades to display by adding or subtracting an error in an input signal for a given pixel to or from peripheral pixels. The error distribution is frequently used to display a natural image on a PDP whose original number of shades is small.
The error distribution, however, causes flicker and peculiar patterns on the PDP. It is necessary, therefore, to provide a technique of increasing the number of shades to be displayed on the PDP without flicker or peculiar patterns.
The problems in the prior art will be explained later with reference to the accompanying drawings.